1. Field of the Invention
The present invention relates to a ballast tamping machine for leveling, lining and tamping a track switch comprising a main track and a branch track comprising a rail laterally adjacent the main track and having a rail head, which comprises a machine frame extending in a longitudinal direction and supported on undercarriages, a tamping unit vertically adjustably mounted on the machine frame and comprising reciprocable vibratory tamping tools, a track lifting and lining unit mounted on the machine frame and comprising lifting and lining drive means, a flanged roller and a lifting tool, and an auxiliary track lifting device associated with the track lifting and lining unit, the auxiliary track lifting device comprising a carrier frame having an end, a tool for gripping the branch track rail mounted on the carrier frame end, an auxiliary lifting drive means, and a displacement drive for adjusting the branch track rail gripping tool on the carrier frame relative to the machine frame.
2. Description of the Prior Art
U.S. Pat. No. 4,893,565 describes such a mobile track working machine especially designed for operation in track switches and crossings. Work in such track sections is difficult not only because of the complicated rail configuration but particularly because of the very heavy weight of the tracks since the main and branch tracks of these track sections are interconnected by very long ties. This very heavy weight which, in addition, is asymetrically distributed, disadvantageously affects the accuracy of the leveling and lining operation. The machine disclosed in the patent comprises a vertically adjustable tamping head, and a track leveling and lining unit engaging the rails by means of flanged rollers as well as rail clamping hooks and lifting rollers. For operation in track switches, an auxiliary rail lifting device is connected at each side of the machine frame to the track leveling and lining unit, each auxiliary rail lifting device comprising a telescopingly extensible carrier frame operable by a displacement drive and extending transversely to the longitudinal direction of the machine frame. At the outer end of the carrier frame there is provided a rail gripping hook, which is vertically adjustable in a vertical guide for engagement with the branch rail, and a similarly adjustable jack, which serves to support the outer carrier frame end on the ballast in the crib and supplies an additional lifting force by means of its own drive.
U.S. Pat. No. 4,825,768 also discloses a ballast tamping machine whose tamping, track leveling and lining tools are adapted for work in track switches. Its auxiliary rail lifting device comprises a frame mounted for mobility on a rail of the branch track and linked to the machine frame by a connecting rod. The frame carries rail gripping tools and a power-driven cable line connects the frame to a telescopingly extensible cantilevered arm mounted on top of the machine. The drive of the cable line enables the frame and its gripping tools to lift the branch track. The auxiliary rail lifting device may be used on either side of the machine frame by horizontally turning the cantilevered arm and its power-driven cable line by 180.degree.. The engagement and disengagement of the auxiliary lifting device take a relatively long time and cannot be effectuated without the manual assistance by an operator.